vim树莓派写python的 树莓派python代码

2.1使用Turtle绘画--画一朵花

打开IDLE3，点击File-->New window,然后输入：

画花朵的第一部分

import turtle

window = turtle.Screen()
babbage = turtle.Turtle()

babbage.left(45)
babbage.forward(100)
babbage.right(90)
babbage.circle(10)

window.exitonclick()

然后点击Run-->Run Module 或者按F5键来运行程序。此时弹出一个对话框让你输入文件名称，这里我们输入：chapter2-example1.py

第二步：画第一片花瓣

import turtle

window = turtle.Screen()
babbage = turtle.Turtle()

babbage.left(45)
babbage.forward(100)
babbage.right(90)
babbage.circle(10)

#add code
babbage.left(15)
babbage.forward(50)
babbage.left(157)
babbage.forward(50)

window.exitonclick()

第三步：画剩余的所有花瓣

import turtle

window = turtle.Screen()
babbage = turtle.Turtle()

babbage.left(45)
babbage.forward(100)
babbage.right(90)
babbage.circle(10)

#update code
for i in range(1, 24):
    babbage.left(15)
    babbage.forward(50)
    babbage.left(157)
    babbage.forward(50)

window.exitonclick()

第四步：给花涂上颜色

import turtle

window = turtle.Screen()
babbage = turtle.Turtle()

babbage.color("green", "green")
babbage.left(45)
babbage.forward(100)
babbage.right(90)
babbage.color("yellow", "yellow")
babbage.begin_fill()
babbage.circle(10)
babbage.end_fill()


#update code
babbage.color("red", "red")
for i in range(1, 24):
    babbage.left(15)
    babbage.forward(50)
    babbage.left(157)
    babbage.forward(50)

window.exitonclick()

2.2一个Python游戏：猫和老鼠

import time
import turtle

box_size = 200
caught = False
score = 0

#functions that are called on keypresses
def up():
    mouse.forward(10)
    check_bound()

def left():
    mouse.left(45)

def right():
    mouse.right(45)

def back():
    mouse.backward(10)
    check_bound()

def quitTurtle():
    window.byte()

#stop the mouse from leaving the square set by box size
def check_bound():
    global box_size

    if mouse.xcor() > box_size:
        mouse.goto(box_size, mouse.ycor())

    if mouse.xcor() < -box_size:
        mouse.goto(-box_size, mouse.ycor)

    if mouse.ycor() > box_size():
        mouse.goto(mouse.xcor, box_size)
       
    if mouse.xcor < -box_size:
        mouse.goto(mouse.xcor, -box_size)

    
#set up screen
window = turtle.Screen()
mouse = turtle.Turtle()
cat = turtle.Turtle()

mouse.penup()
mouse.penup()
mouse.goto(100, 100)

#add key listeners

window.onkeypress(up, "Up")
window.onkeypress(back, "Back")
window.onkeypress(left, "Left")
window.onkeypress(right, "Right")
window.onkeypress(quitTurtle, "Escape")

difficulty = window.numinput("Difficulty", "Enter a difficulty from easy(1), for hard(5)",
 minval = 1, maxval = 5)

window.listen()

#main loop
#note how it changes with difficulty

while not caught:
    cat.setheading(cat.towards(mouse))
    cat.forward(8 + difficulty)
    if cat.distance(mouse) < 5:
        caught = True
    time.sleep(0.2 - (0.01 * difficulty))
window.textinput("GAME OVER", "Well done. You scored:" + str(score * difficulty))
window.byte()

 

2.3小结

1.Python程序由一系列命令组成并从上到下执行

2.可以通过循环和if语句控制程序的执行顺序

3.不必事必躬亲，通过倒入模块，使用模块中的的方法可以完成许多工作

4.函数可以帮助重用代码，也可以使程序变得易于理解和维护

5.变量可以存储信息以便后面使用